Since 91422704d965268f, specifying a font that is not registered with pdfmetrics will raise an exception. Now, improve that exception to help the user understand what has gone wrong. Note: rather than hiding the fact that some font is missing, the admin should see this error and try to either fix the report (to use a known font), or register more fonts with the customfonts.py mechanism. bzr revid: p_christ@hol.gr-20101123153235-c1yri33ptaydb5eo